APRIL 9, 1991
DERECHO
"The West Virginia Derecho of 1991"
Figure 1. Area affected by the April 9, 1991 derecho event (outlined in blue). Curved purple lines represent the approximate locations of "gust front" at three hourly intervals. "+" symbols indicate the locations of wind damage or wind gusts above severe limits (measured or estimated at 58 mph or greater). Red dots and paths indicate tornado events.
On the morning of Tuesday, April 9, 1991, a bow echo developed over eastern Arkansas (AR) and began producing wind damage. As the day progressed a serial derecho developed as the original bow echo raced northeastward and expanded in scale and an additional bow echo developed farther north (Fig. 1). Two people were killed and 145 were injured by this storm. Most of these casualties resulted from falling trees, flying debris, and mobile homes being overturned or destroyed. The most destructive damage extended from western Tennessee (TN) through Kentucky (KY) and West Virginia (WV) into western Maryland (MD) and southern Pennsylvania (PA). Winds along this band exceeded 80 to 100 mph at some points. Literally thousands of buildings and mobile homes were damaged or destroyed. In West Virginia alone there were insurance damage claims for 8000 homes and businesses. Over 200,000 West Virginia customers lost electrical power during this derecho event. Flickering lights and power surges preceded the arrival of the derecho, foretelling many residents that something unusual was happening. The 2 deaths and 86 of the injuries also occurred in West Virginia. It was the worst severe thunderstorm event in West Virginia since the tornado super outbreak of April 3, 1974.
John Hart, a National Weather Service forecaster at Charleston, West Virginia at the time, was at the weather forecast office when this event took place. The office was near the airport just northeast of the city and a few hundred feet above the valley. As the bow echo rapidly approached the city around 6 PM EDT, John looked west to view the storm and it appeared as a "big black mass". During the last couple of miles before the gust front reached the office, he observed frequent bright blue "flashes" from short-circuiting power lines against the very dark background of the storm. The very heavy rains and the gust front with its ragged low clouds reached the office at the same time with the rain blowing in nearly horizontal sheets as the airport anemometer registered a maximum wind gust of 66 mph. The severe winds lasted about 5 minutes although the heavy rain continued for quite a while longer. As the derecho passed through the Charleston metropolitan area 1 person was killed when a mobile home was overturned and fell down an embankment and 60 others were injured mostly from flying debris and falling trees.
(References.....Duke and Rogash, 1992; Storm Data for April 1991)